1. Technical Field
The present invention relates to a printing method using an inkjet recording method for printing on non-ink-absorptive and low-ink-absorption recording media and to a printing method using an inkjet recording method that is excellent in terms of image quality, resistance to abrasion, and discharge stability no matter how ink-absorptive recording media used therewith are.
2. Inventions of the Related Art
[Background Art]
Inkjet recording is a recording method in which ink droplets are jetted (discharged) so as to attach a recording medium, such as paper, for recording. Recent drastic advancements in inkjet recording technologies have put inkjet recording into practice also in recording (printing) of fine images, replacing silver halide photography and offset printing. This requires ink for inkjet recording to have some mandatory properties, for example, long-term stable discharge of droplets for resultant images having no defects.
An example of ink for inkjet recording is one proposed in Japanese Patent No. 3509013 (Patent Document 1), which is a pigment ink obtained as a combination of an acetylene-glycol surfactant, triethylene glycol monobutyl ether, 2-pyrrolidone, and a water-soluble organic solvent and is described as being favorable in terms of discharge stability and clogging reliability. Also, Japanese Unexamined Patent Application Publication No. 2005-120181 (Patent Document 2), Japanese Unexamined Patent Application Publication No. 2005-263967 (Patent Document 3), and Japanese Unexamined Patent Application Publication No. 2005-263969 (Patent Document 4) each propose a pigment ink containing a silicon surfactant and describe that the ink is excellent in terms of stability in serial printing and produces images having a reduced number of blurs. Furthermore, Japanese Unexamined Patent Application Publication No. 2006-316243 (Patent Document 5) proposes a pigment ink containing a fluorine surfactant and describes that the ink produces a reduced number of blurs and is favorable in discharge stability. All of these inks have been proposed as methods for printing on highly ink-absorptive recording media.
A printing method for producing images using an inkjet recording method on non-ink-absorptive and low-ink-absorption recording media is proposed in Japanese Unexamined Patent Application Publication No. 2000-44858 (Patent Document 6), which proposes an ink containing water, a glycol-based solvent, an insoluble colorant, a polymer dispersant, a silicon surfactant and a fluorine surfactant, a water-insoluble graft copolymer binder, and N-methyl pyrrolidone as a method for printing on hydrophobic base materials. Also, Japanese Patent No. 3937170 (Patent Document 7) proposes an ink composed of an aqueous emulsion polymer having a glass transition temperature in the range of 40° C. to 80° C., a pigment, and a water-soluble surface agent selected from a monoalkylether of an alkylene glycol, 2-pyrrole, N-methylpyrrolidone, and sulfolane as a method for providing images on hydrophobic surfaces. Japanese Unexamined Patent Application Publication No. 2005-220352 (Patent Document 8) proposes a polymer-colloid-containing inkjet ink for printing on nonporous base materials, which is composed of a volatile cosolvent having a boiling point equal to or lower than 285° C., polymer colloid particles having acidic functional groups, and a pigment-based colorant.
Japanese Unexamined Patent Application Publication No. 2004-195451 (Patent Document 9) proposes an overcoat composition for highly resistant printed images, which contains an aqueous carrier, a humectant, a surfactant, and an additional polymer exhibiting an acid value of higher than 110. In addition, Japanese Unexamined Patent Application Publication No. 2000-44858 (Patent Document 6) mentioned above proposes a printing method including a step of applying an overcoat composition obtained by removing a colorant from an ink composition.
However, non-ion-absorptive and low-ion-absorption recording media have no layers for absorbing ink and developing the color of the ink; thus, they are inferior to inkjet recording media, which are highly absorptive, in terms of color reproduction and have the problem of developing insufficient colors when the inks described above are used. In particular, black letters are difficult to record on both non-ink-absorptive and low-ink-absorption recording media with a sufficient darkness using a single kind of ink.
Incidentally, low viscosities of ink are favorable in rapid printing of high-resolution and high-quality images; however, ink having too low a viscosity has the problem of an insufficient resistance to abrasion because of its low capacity for colorants and resin components. When containing large amounts of colorants and resin components, such a low-viscosity ink hardly ensures sufficient discharge stability.
Meanwhile, Patent Documents 6 and 9 each disclose a method for providing an ink with a high resistance by applying an overcoat composition to printed images. However, these methods have the problem that the relatively small coating thickness of the applied ink leads to an insufficient coating strength.
[Patent Document 1] Japanese Patent No. 3509013
[Patent Document 2] Japanese Unexamined Patent Application Publication No. 2005-120181
[Patent Document 3] Japanese Unexamined Patent Application Publication No. 2005-263967
[Patent Document 4] Japanese Unexamined Patent Application Publication No. 2005-263969
[Patent Document 5] Japanese Unexamined Patent Application Publication No. 2006-316243
[Patent Document 6] Japanese Unexamined Patent Application Publication No. 2000-44858
[Patent Document 7] Japanese Patent No. 3937170
[Patent Document 8] Japanese Unexamined Patent Application Publication No. 2005-220352
[Patent Document 9] Japanese Unexamined Patent Application Publication No. 2004-195451